Plotting instrument



Patented Dec.v 26, 1,944

" UNITED STATES TENT L OFFICE PLo'r'rING INSTRUMENT v Charles Fremont Golden, Denver, l l Application Janary 25, 194s, serial' No. 473.5120` i claim.' (c1. ,ss- 75) This invention relates to a plotting instrument and it is more especially an improvement upon the structures shown in my patents, 1,869,358 and 2,104,515.

An object'of the invention is to provide a simple and compact instrument designed for use in plotting by bearings, azimuth and traverse, the several parts of the instrument being combined in sucha manner as to permit continuous plotting accurately, conveniently and speedily.

Another object is to provide an instrument of this character which canbe used in practically all elds where drafting and designing of equipment is necessary. t

A still further object is to provide two protractors so graduated as tomake it possible to cover the complete circle in azimuth layouts, it being possible to use the instrument as a T- square, a compass, at least ve-scales, `a paralleler, and Vernier. f

Another object is to provide an instrument the edges of which are so formed that it can beused in inking without danger of smearing.

With the foregoing and other objects in View which will appear as the description proceeds, the invention consists of certain novel details of construction andcombinations of parts hereinafter more fully described and pointed out in the claim, it being understood that changes may be made in the construction and arrangement of parts without departing from'the spirit of the invention as claimed.

In the accompanying drawing the preferred form of the invention has been shown.

In said drawing l Figure l is a plan Aview of the instrument, the

extension arm being shown by brokenlines in folded position.

Figure 2 is a section on line 2-2, Figure 1, said section showing a portion broken away.

Figure 3 is a section on line 3 3, Figure 2. Figure 4 is a section on line 4 4, Figure 2. Figure 5 is a section on line 5 5, Figure 2.

Figure 6 is a bottom plan View kof one end por-A tion of the instrument, a portion of the extension arm being shown folded, the extended position of said arm being shown by broken lines.

Figure 7 is a bottom plan view of the free end portion of the extension arm and its guard or keeper.

Figure 8 is a section on line 8 8, Figure 7. Figure 9 is a view similar to Figure 4 but showing a modied construction.

Referring to the gures by characters of reference, I designates the elongated nat blade ol ing webs 1.

the instrument which, as shown in Figs. 4 and 5,

has the bottom portions of its side edges beveled as at 2 so that, while the instrument is being used for inking, there is no danger of smearing the work. The edgesof the blade are straight and one of these straight edges, 3, is extended to the center ofthe straight side 4 of a semicircularyhead or protractor 5 which is integral with the blade. The graduations 5a on the outer edge of the protractor are extended through and, for the purpose of providing other scales in this part of the instrument, an arcuate slot 6 extending through 180 is provided, this slot being interrupted at its center by spaced connec- Thus three arcuateedges within a range of 180 are provided along which any desired graduations'canbe located. For example one of the protractors can be graduated in mills and the other indegrees and thirty minuter readings, the degree markings being specially arranged so as to make it possible to cover the complete circle in azimuth layouts. In order to permit the extension of the slot 6 through 180 degrees, the straight edge 4 is offset at its ends as shown at 8.

Located at the point where the straight edges 4 and 3 meet, there is a. centering pin 9 `carried by a bracket I0 on the head 5, this pin being shiftable longitudinally as desired. It can be of a construction already well known.

A longitudinal slot II is provided in the blade I. The slot is parallel with the edge 3 and also with the opposed edge I2 of the blade. One end vof the slot is in line with the edge 4 while the other end terminates adjacent to the free end of the blade. 'I'hat portion of the blade between edge 3 and slot I I is of greater thickness than that part of the blade, between slot II and edge I2, the thicker portion of the blade extending longitudinally thereof being indicated at I3. An extension blade I4 having parallel straight edges is adapted to extend longitudinally of the blade along the bottom surface of the thin portion thereof and this extension has an ear I5 at one end extending at right angles therefrom and pivotally joined to the blade I as shown at I6. vThis pivot is located adjacent the slot II and to the free end of the blade. Adjacent to the other end of the blade there is a keeper in the form o1 a diagonally disposed undercut shoulder I'I and the free end of the blade is beveled, as at I8 so as to wedge into engagement with the shoulder as shown in Fig. 7 with the outer straight edge of the blade close to and parallel with the edge |2. The parts I5 and I3 are so located that when blade I4 is swung outwardly about pivot I 6 it will 

